Silver in palladium white gold?

I know there are some palladium gold alloys that contain only
palladium and gold, while there are others that also contain silver.
Is there any chance that having silver in there will make a piece of
jewelry tarnish?

Overall, what is the best type of palladium white gold for someone
concerned about non-yellowness, durability, and longeveity?
Normally I would recommend 75% gold, 25% palladium, but that is
because I have never seen a 14k palladium white gold piece. Is the
14k alloy whiter?

Greg Starbird